They struggle to produce it cheaply enough, at least as of right now. Manufacturing, at scale and within costs is really really hard. Tesla's initial math for cracking the economy was based on full automation of the production, that failed spectacularly. As a result they have a lot of human labor costs they didn't plan for, so problem of optimizing it got even harder.
Did Tesla made desirable product? Yes, of course. Can they crack the economy of it? We'll see.
You’re correct that Tesla’s future and costs are uncertain, but that’s irrelevant. What is relevant is that the production cost of a Model 3-type EV will never be as high as it was in 2018. It will never be as high as it is in 2019. Even without miraculous supply chain improvements, the cost of lithium batteries and electric drivetrains is on a relentless downward path. If Tesla can make one now at $10 in profit (obviously they make more than that), then whichever company is doing so in 5-8 years will be earning thousands in profit. And if the manufacturer is not BMW, it will be the end of that company as a viable competitor.
Investors can lose their shirt on a viable company. Just as they can make bank on a company that's a flash in the pan. Investors can often make money on companies that are actually failing and going to fail. There is probably an correlation between how hardball the company plays it's investors and the companies ultimate viability.